SUMMARY- Research Project 1- Metals and metal mixtures in DNA damage and repair The Native Environmental Health Equity Center seeks to address environmental health disparities and health concerns of three Native American communities (Navajo Nation, Cheyenne River Sioux Tribe and Crow Reservation) arising from exposure to mine waste metal mixtures. The communities are exposed to distinct metal mixtures with overlap in certain metals of primary concern: uranium (U), arsenic (As), manganese (Mn) and mercury (Hg). The proposed research is grounded in 1) documented community exposures, 2) evidence for increased body burden of metals of concern within the communities, and 3) evidence that exposure is linked to adverse effects. Each of the four metals identified by the tribal community partners share likely mechanisms of action such as generation of oxidative stress and disruption of zinc finger protein function. These shared mechanisms are predicted to amplify the toxicity of combined exposures compared to single metal exposure. This project will investigate each metal of concern and community-relevant metal mixtures in samples derived from the affected populations (Aim 1) and conduct mechanistic experimental studies (Aim 2). Both aims are designed to test the hypothesis that As, U, Mn and Hg (individually or in combination) will inhibit the function of a prototypic zinc finger DNA repair protein (PARP-1) and impair DNA repair processes leading to increased retention of DNA damage, and that metals in combination will exacerbate adverse response compared to single metal exposure. We have published and preliminary findings indicating interactions between As and U, disruption of zinc finger protein function by these metals, and evidence that supplemental zinc is protective against A or U interaction with zinc fingers. The experimental observations are confirmed in a preliminary analysis of an exposed human population from the Navajo Nation. The proposed studies enhance understanding of the impact of metals and metal mixtures in the Native communities, and the controlled in vitro and cell based assays will provide mechanistic insights on the actions of metals and metal mixtures at concentrations relevant to the communities, and additionally determine whether zinc is protective against the effects of metals individually or in combination. The research is relevant to the goals of the Native Environmental Health Equity Center and significant by providing important information to improve understanding of environmentally driven health disparities due to toxic metals exposures while being responsive to the concerns of the affected communities. Furthermore, our studies to investigate whether zinc can mitigate the effects of metals and metal combinations will serve as critical mechanistic foundations for potential future population and intervention studies in vulnerable communities. Overall, the proposed project represents transdisciplinary and translational research to advance understanding, mitigation and prevention of environmentally driven health disparities which is a stated goal within the program.